A rupture disk is disclosed in co-owned U.S. patent application Ser. No. 12/923,622, filed Sep. 29, 2010, by John Tomasko, Paul Goggin, and Geof Brazier, and titled RUPTURE DISK, the disclosure of which is hereby expressly incorporated herein by reference. A rupture disk is also disclosed in co-owned Patent Cooperation Treaty Application No. PCT/US10/50779, filed Sep. 29, 2010, by John Tomasko, Paul Goggin, and Geof Brazier, titled RUPTURE DISK, and published as PCT Pub. No. WO/2011/041456, the disclosure of which is hereby expressly incorporated herein by reference.
A rupture disk is used to release pressure from a pressurized system in response to a potentially dangerous overpressure situation. Generally, a rupture disk has a flange that is sealed between a pair of support members, or safety heads, forming a pressure relief assembly. The pressure relief assembly may then be clamped or otherwise sealingly disposed between a pair of conventional pipe flanges or between a pair of threaded fittings, or attached to one such threaded fitting, in the pressurized system. The pressure relief assembly may be installed using such techniques as welding, soldering, crimping or mechanical clamping to hold the sandwich of components together. A first pipe conducts pressurized fluid to one side of the pressure relief assembly, and a second pipe provides an outlet to a safety reservoir or may be open to the environment. The support members include central openings that expose a portion of the rupture disk to the pressurized fluid in the system. The exposed portion of the rupture disk will rupture when the pressure of the fluid reaches a predetermined differential pressure between the inlet and outlet sides. The ruptured disk creates a vent path that allows fluid to escape through the outlet to reduce the pressure in the system.
A rupture disk may also be used to relieve pressure from a system without being placed between two pipe flanges. For example, a pressurized system may have an outlet member or opening through which fluid may be vented or released—e.g., into the environment or a container. A rupture disk may be installed at such an outlet member or opening to control the pressure at which fluid may be released. For example, a rupture disk may be welded to an outlet member or welded to cover an outlet opening. Additionally or alternatively, a rupture disk may be attached to a pressurized system's outlet by clamping, bolting, riveting, or any other suitable mechanism.
A rupture disk typically has a dome-shaped, rounded-shaped, conical shape, truncated conical shape, or other generally curved rupturable portion and can be either forward-acting or reverse-acting. A forward-acting rupture disk is positioned with the concave side of the rupturable portion exposed to the pressurized system, placing the disk under tension. Thus, when an over-pressure condition is reached—i.e., when the system pressure exceeds a safe or desirable level—the rupture disk may release pressure by bursting outward. Conversely, a reverse-acting rupture disk (also known as a reverse buckling rupture disk) is positioned with its convex side exposed to the pressurized system, placing the material of the disk under compression. Thus, when an over-pressure condition is reached, the rupture disk may buckle and reverse—i.e., invert—and tear away to vent pressurized fluid.
A reverse buckling rupture disk may rupture by itself upon reversal. Alternatively, additional features may be provided to facilitate rupture. For example, a cutting structure or stress concentration point may contact the reverse buckling rupture disk on reversal, ensuring that rupture occurs. Exemplary cutting structures include one or more blades (e.g., a four-part blade like that provided by BS&B Safety Systems as part of the commercially available RB-90™ reverse buckling disk, or a tri-shaped three-part blade like that provided by BS&B Safety Systems as part of the commercially available DKB VAC-SAF™ rupture disk) and circular toothed rings (e.g., like that provided by BS&B Safety Systems as part of the commercially available JRS™ rupture disk). Other exemplary cutting structures may be positioned along the periphery of a rupturable portion. Still other exemplary cutting structures may be positioned in an X-shape, Y-shape, or irregular Y-shape designed to engage with the rupturable portion upon reversal.
Rupture disk assemblies using cutting structures are described in co-owned U.S. Pat. Nos. 4,236,648 and 5,082,133, the contents of which are hereby expressly incorporated by reference in their entirety. Exemplary stress concentration points are described in co-owned U.S. Pat. No. 5,934,308, the contents of which are hereby expressly incorporated by reference in their entirety.
The predetermined pressure differential at which a rupture disk will rupture is known as the “burst pressure.” The burst pressure for which a rupture disk is rated is known as the “nominal burst pressure.” The burst pressure may be set by way of the rupture disk's physical parameters, such as material thickness and dome height (also known as “crown height”). The burst pressure also may be set using various physical features, such as indentations. A rupture disk having an indentation—and methods of manufacturing such rupture disks—is disclosed, for example, in co-owned U.S. Pat. Nos. 6,178,983, 6,321,582, 6,446,653, and 6,494,074, the contents of which are hereby incorporated by reference in their entirety.
Physical features, such as score lines and shear lines (and other areas of weakness, also known as lines of weakness), may be used to facilitate opening of a rupture disk and control the opening pattern of a rupture disk. In a reverse buckling disk, for example, the disk will tear along a score line when the disk is reversing. A score or shear line may be used in combination with a stress concentration point or cutting member. Selected portions of the disk may be left unscored, acting as a hinge area, to prevent the disk from fragmenting upon bursting and the fragments from the disk escaping along with fluid from the pressurized system. A central portion of the disk that is partially torn away from the rest of the disk may be referred to as a “petal.”
Fragmentation of a rupture disk is also controlled through use of a transition area. The transition area appears between a rupture disk's dome and flange portions. The rupture disk industry has focused on using a transition area with a fixed radius to assist with fragmentation control.
Fragmentation may also be controlled through the use of a peripheral hinge located downstream of a rupture disk. The industry has typically focused on achieving the maximum open area possible from a rupture disk device, at least in part to maximize the flow rate when the rupture disk device activates or opens. As a result of that focus, a known rupture disk device has typically minimized the open area occupied by a downstream peripheral hinge. Usually, a downstream hinge occupies less than 15% of the possible opening area.
In light of the foregoing, it may be desirable to combine one or more of the foregoing features to ensure reliable performance of a rupture disk, and to prevent fragmentation of a rupture disk. It may be desirable to avoid reinforcing a score line or other area of weakness after the domed structure collapses. It may also desirable to provide support to an unscored hinge area of a rupture disk, to prevent the disk from fragmenting upon bursting. Alternatively, it may be desirable to reinforce a portion of the scored area of a rupture disk, to arrest the tearing of the score line and effectively create a hinge to retain the rupture disk petal. It may also be desirable to provide a feature that may absorb burst energy from a burst rupture disk. For example, it may be desirable to absorb the kinetic energy of a rupture disk petal to decelerate the petal. The rupture disk and hinge assembly of the present disclosure achieve these, or other, advantages.